I get a message on my status bar for my G mail account that it is 77% full. There is hardly anything in that account...maybe 100 or so messages. The 77% never changes. On the other hand, my main account has several GBs of mail in its folders and there is no such message in the status bar. Just wondering what's up?

In general deleting a message just marks it as deleted and hides it from view, it still takes space. Try running Thunderbird in safe mode (help -> restart with add-ons disabled) to see if your problem is a side effect of an add-on.

The quota in the properties for my first gmail account says 254361 of 122683382 KB used. 0%full. I would normally expect something like 15GB for the upper limit, not 122.7 GB. My second gmail accounts inbox says 6282 of 15728640 KB used. 0% full. That one seems correct (15.7 GB upper limit). So it seems there is a bug that effects at least one of my gmail accounts quota.